The wastewater industry has responded to increasingly stringent plant effluent requirements with enhanced plant design and innovative technology. While these new procedures are able to treat higher volume flows for less money, these procedures require significant attention to each stage of the improved processes. It is generally accepted that unique plant designs have established and defined performance requirements in order to meet effluent regulations, but increasing emphasis on influent flow analysis is needed to optimize treatment.
Engineers, operators, and maintenance personnel alike have long since realized there are benefits in removing inorganic and settleable solids as early in the treatment process as possible, but preliminary treatment equipment has conventionally been selected more on requirements of downstream processes than influent characteristics. Specifically, as these processes increase in sophistication and sensitivity, plant design is driven towards finer upstream screening protection without further investigation into the type of solids presented to the plant. Generally, this can result in higher capital outlays, larger headworks structures, and frequently increases disposal of the organic and fecal material the plant is designed to treat.
Just as each plant has its own characteristics that dictate the amount of screening protection it requires, every collection system and the waste flow it receives are unique as well. The design of a collection system, constituents feeding the plant, stormwater infiltration, and variations in flow all have a direct impact on the quantity, size, and consistency of screenings in the influent flow of any given treatment plant. The Water Environment Federation (WEF), in co-operation with American Society of Civil Engineers (ASCE), did a study of the screenings volume relative to flow collected at 39 U.S. wastewater treatment plants. Their results proved that plant screenings are so unique they differ by a factor of 70 times. Even conservative sizing used by most screen manufacturers cannot properly account for fluctuations in screenings of this magnitude when calculations are based on peak flow and opening size alone.
What is needed is a method and system for testing with specialized equipment, which may analyze the solids loading characteristics of an individual plant to be expanded from generalized total suspended solids (“TSS”) or biochemical oxygen demand (“BOD”) ranges to stratification of solid sizes present in the waste stream. What is needed is a method and system for analysis of this data that help identify proper screen openings and capture ratios required by downstream processes while determining the appropriate screen type, size, and operational sequence determined by the unique inputs to the individual plant.